The paper evaluates the measurement uncertainty in realizing the secondary vibration standard at CSIR-National Physical Laboratory, India, and presents a comparison of the measurement uncertainty of secondary standard with that of primary vibration standard. The relative expanded measurement uncertainty of 0.80% to 2.2% in frequency range of 5 Hz to 10 kHz is evaluated. The measurement uncertainty so calculated is verified by comparison with the results from primary vibration calibration standard of CSIR-National Physical Laboratory, New Delhi, and SPEKTRA Schwingungstechnik und Akustik GmbH Dresden, Germany primary calibrations. The study recommends calibrating the back-to-back accelerometer with minimal uncertainty by using a primary calibrated single-ended accelerometer mounted on the top of the back-to-back transducer.The paper serves a guiding document to the calibration laboratories, industries and other stake holders in India to understand the concept of traceability in vibration measurements and formulation of uncertainty budget as per the international standard
